1. Field of the Invention
The present invention is broadly concerned with improved corrosion inhibitor formulations specifically adapted for incorporation into deicing road salts. More particularly, the invention pertains to such corrosion inhibitors, and to mixtures thereof with road salts, wherein the inhibitors contain respective amounts of a first component selected from the group consisting of citric acid, salts of citric acid, and mixtures thereof, and a second component selected from the group consisting of alkali metal silicates, alkali metal metasilicates, and mixtures thereof. Use of the corrosion inhibitors of the invention materially lessens the corrosive effect of the road salts on metal surfaces, and is also believed to have an ameliorating effect upon corrosion of concrete surfaces.
2. Description of the Prior Art
Municipalities and highway departments use vast quantities of road deicers during wintertime to deice roadways. The most traditional deicer is simply coarse sodium chloride. In recent years, mixed salt deicers have also been employed, e.g., sodium chloride mixed with calcium magnesium acetate (CMA) or magnesium chloride.
A serious problem with prior road deicers has been their corrosive effective on concrete and metal surfaces. For example, heavy use of road deicers can lead to powdering of concrete surfaces and rapid deterioration of metal reinforcing rods in poured concrete roadways and bridges. Use of CMA in traditional sodium chloride deicers is thought to reduce the corrosive effects thereof, but CMA is a very expensive chemical in the context of road deicers. Likewise, attempts have been made to use magnesium chloride with sodium chloride deicers for corrosion inhibition purposes. While some improvement in corrosive properties is obtained, magnesium chloride is expensive, large amounts are required, and the additive adversely impacts upon the handling properties of the deicer (e.g., the hygroscopic nature thereof leads to clumping during storage).
There is accordingly a need in the art for an improved corrosion inhibitor adapted for addition to otherwise conventional road deicer compositions which are low in cost and do not detract from the handling and use characteristics of the road deicers.